Hypoxic-Ischemic Encephalopathy and Beyond: A Pictorial Review of Neuroimaging Findings in Neonatal Encephalopathy.

Neonatal encephalopathy (NE) encompasses a broad spectrum of neurological dysfunction in newborns, presenting with varying degrees of severity and diverse etiologies. This pictorial review aims to provide an overview of imaging findings associated with NE, highlighting both common and uncommon presentations. By focusing on hypoxic-ischemic encephalopathy (HIE), neonatal stroke, metabolic encephalopathy due to inborn errors of metabolism, central nervous system infections, and structural/genetic causes, this review underscores the importance of accurate diagnosis and management through neuroimaging. Evaluating neonatal imaging for signs of encephalopathy requires meticulous attention to specific characteristics associated with various etiologies. The neonatal brain exhibits distinct myelination patterns, and recognizing normal imaging in full-term and preterm neonates is essential for identifying abnormalities. HIE can manifest with distinct signal changes depending on the injury pattern, which can be either severe total hypoxia, prolonged partial hypoxia, or a combination of these. Magnetic resonance imaging (MRI), particularly diffusion-weighted imaging (DWI), is helpful in detecting these changes. Metabolic encephalopathies often present with overlapping imaging features, and identifying the primary pattern of involvement, such as white matter, deep gray matter, or a combination, serves as a starting point for differentiating etiologies. In cases of neonatal brain infections, contrast-enhanced MRI can detect early involvement of the meninges, ependymal lining, and brain parenchyma, with DWI being particularly useful for identifying ischemic areas and purulent accumulations that may not be visible with other imaging modalities. Structural and genetic causes of NE can lead to specific imaging findings that are crucial for accurate diagnosis and tailored management.